Jailed: Darcy O'Sullivan, known as Marist Brother Dominic, outside court before his first conviction for child sex offences against eight former students. He has pleaded guilty to offences against another 15 former students.

THE Marist Brothers thought so little of more than two decades of child sexual abuse complaints against Darcy O’Sullivan – Brother Dominic – that the order appointed him principal of its Hamilton high school in 1996.

But he never did become principal after the new Maitland-Newcastle Catholic Bishop Michael Malone received complaints within hours of Brother Dominic’s appointment and rang the order.

In Sydney District Court on Thursday O’Sullivan, 79, entered guilty pleas to 30 offences against 15 former students of Marist Hamilton College and St Mary’s High School at Casino, including seven counts of sexual assault.

The pleas came less than two years after he pleaded guilty to 22 offences against another eight students at Marist schools at Hamilton and Casino in the 1970s and 1980s, and while he was completing a maximum six year jail sentence for those offences.

“You could say that for someone who led a fairly indecent life, the guilty pleas are the most decent thing he could do,” said a former student who was sexually abused on multiple occasions while a year 8 student at the Hamilton school in the 1970s.

“It doesn’t alter the fact it’s been part of something that’s f...ed my life,” the former student said.

Brother Dominic was “completely careless” about his offending while at the Marist Hamilton school, the former student said.

“It was like we were a smorgasbord to him. He would take you out of the classroom into a storeroom and he’d just go for it. He’d do it on the veranda where anyone could see. He’d push you up against the wall and when he was finished he’d take you back in and take another boy out.

“It was like he had open slather. After what we heard at the royal commission we now know that was true.”

The second lot of guilty pleas on Thursday came after damning evidence of extensive Marist Brothers knowledge of Brother Dominic’s offending to a Royal Commission into Institutional Responses to Child Sexual Abuse hearing in Newcastle in 2016.

Guilty: Marist Brother Dominic - Darcy O'Sullivan - pleads guilty to offences against 15 former students while completing a jail sentence for offences against a further eight former students.

The commission heard from a number of former senior Marist Brothers who confirmed knowledge of complaints against Brother Dominic, who was moved to new areas after matters were raised.

After Bishop Malone raised complaints with Marist provincial Michael Hill the order’s provincial council met and minutes recorded that: “Brother Dominic O'Sullivan is unable to go to Hamilton next year because of health reasons. Discussion on the possible replacement for Brother Dominic took place.”

Brother Michael told the royal commission he had “no specific memory of that particular discussion” but agreed the minutes were “misleading”.

He agreed with commission chair Justice Peter McClellan that “It looks like someone’s trying to hide the truth”.

The order sent Brother Dominic to an American program, Wellsprings, in 1997, to address his problems with what Brother Michael called “boundary violations”.

Brother Michael told the royal commission he considered sending O’Sullivan to Fiji but O’Sullivan objected, and he didn't force the issue.

Marist records show the provincial council considered sending O’Sullivan to major Marist Brothers colleges at Dundas or Ashgrove in Brisbane but the principals of both schools objected.

“It disgusts me that people in the Marist Brothers knew so much about Brother Dominic and did nothing. They could have saved so many people from having their lives devastated by this predator but they just moved him on,” the former student said.